Tuesday, July 19, 2011

60 Tons of Nitrogen Oxide Per Compressor Station Will Not Work In The Marcellus

The Air Quality Study commissioned by Fort Worth to measure the impact of shale drilling on its air is a trove of important data (see earlier posting) and the consultants concluded that emissions to date caused no significant health impact.

But the study has a warning light for the Marcellus, as it reports that 8 compressor engines servicing production from 375 wells are emitting about 500 tons of nitrogen oxide per year or about 60 tons per engine.

The Marcellus air shed will not support 60 tons of nitrogen oxide per compressor engine. Pennsylvania's total nitrogen oxide emissions from all sources was about 180,000 tons in 2010.  And that amount must decline substantially to comply with the Clean Air Act.

If one takes the ratio of compressor stations to gas wells of 1 engine for every 46 gas wells that is implied by the Fort Worth data, 3,300 Marcellus wells now drilled would require approximately 76 compressor stations and hundreds in the future.

This is rough, back of the envelope analysis, but hundreds of compressor stations plus more than a hundred drilling rigs, if each is running on the dirtiest fuels with least controls, could produce so much nitrogen oxide as to compromise meeting legally mandated air quality standards.  Wyoming is now dealing with smog in counties where no smog existed as a result of drilling nitrogen oxide emissions.  This problem is not hypothetical.

A compressor engine producing 60 plus tons of nitrogen oxide is likely running on diesel without the best pollution controls.  The same engine running on electricity or gas with top pollution controls would emit about 5 tons per year.

The Clean Air Act's nitrogen oxide requirements can be met by deploying the clean engines and will not be met if the 60 plus ton emitters are installed throughout Pennsylvania.


  1. http://www.post-gazette.com/pg/11056/1127950-100.stm

    A few months old, but it merits a review based on the findings in Texas.

    However, a DEP study of air quality in the Northeast concluded no issues... http://www.post-gazette.com/pg/11140/1147855-113.stm

    Guess we'll be behind the eight ball again in a few short years?

  2. Those are startling numbers. I certainly hope that companies utilize natural gas moving forward with these compressor stations. All of the compressors I have personally come across here in Western PA run on natural gas. Is there some sort of benefit to run on diesel? One would think that natural gas would be obvious fuel of choice, since it's right there, its cheaper, burns cleaner which means less maintenance, etc.

  3. Nat:

    To be clear the issue I am raising is about nitrogen oxide and about the cumulative emissions of nitrogen oxide given two scenarios. No one compressor or handful of compressors emit enough nitrogen oxide to cause a problem no matter what. But if there are hundreds of compressors and there will be, then the cumulative emissions of nitrogen oxide could be a problem or will not be a problem depending on how much emission comes from each engine. If the average emission is about 60 plus tons across the whole Marcellus, then it will be a big air quality/Clean Air Act problem. If the average per compressor/emission is closer to the clean end of the spectrum--about 5 tons per compressor--then it will not be an air quality/ Clean Air Act problem.

  4. Mr. Hanger:

    Perhaps a bit too much sarcasm in my previous post, but I understand. We can extrapolate from the data and arrive at two extremes based on industry practises. Technology and B.M.P.s exist that if implemented, then we should not have air quality issues. However, if we are obtaining baseline data without cumulative analysis, then will we have sufficient information in the out years to know with certainty that industry is operating well within air quality limitations? Is there anything industry or government can do to ensure what little "budget" is left in our air quality is not exhausted by this uptick in the local energy economy?

  5. Concerned ScientistJuly 20, 2011 at 9:50 AM

    Mike Knapp brings up a good point and cites another thing that environmental groups that actually care about the environment could and should fight for: running as much equipment as possible on natural gas.

    Natural gas is a winner for the environment when compared with the other realistic alternatives. Environmental groups should support responsible natural gas development and building a natural gas infrastructure to decrease coal and then oil consumption. What groups could and should fight for is to see that development done in the most environmentally friendly way. Making stuff up about neurotoxins, carcinogens and radioactivity getting in the water is irresponsible and not helpful to people who really want to have a clean environment and a cooler planet for future generations. All that does is keep us burning coal and oil.

    Along with running equipment on natural gas, things environmental groups should fight for:

    Limiting flaring and emissions of methane during drilling and fracking (emissions are still way lower than coal but could be lower still)

    Decreasing surface footprint through drilling more wells from a single pad and drilling longer laterals.

    Limiting truck trips through recycling of fluids on site and perhaps withdrawing water onsite from wells constructed in advance.

    Working with companies to site and camouflage wells so they can't be seen

    Supporting the DEP, DEC and other regulatory agencies and demanding that they have the resources and power to regulate effectively

    Supporting real studies to better understand and then effectively mitigate the problem of methane migration (which is not nearly as common as some make it out to be, but is a problem nonetheless)

    Policing their own and making sure they get educated on what really matters for people who care about the environment more than they care about being against oil companies.

    I realize that serious environmentalists who would take such an approach might appear to be allying themselves to some degree with oil companies and that this may seem distasteful. Oil companies have made effective bogeymen for decades. Nothing gets the cash register ringing and the righteous indignation going like a fight with an oil company. But the holy war may have to be set aside for the good of the planet.